

K = [ 10, 0, 0, 0; 2, 5, 0, 0; 1, 0, 4, 0; 0, 0, 3, 5];
K = K + tril(K, -1)';
K 
F = ones(4, 1)




K = [1, 1, 0, 0, 2, 2
     1, 1, 0, 0, 2, 2
     0, 0, 0, 0, 3, 3
     0, 0, 0, 0, 3, 3
     4, 4, 5, 5, 6, 6
     4, 4, 5, 5, 6, 6];
F = ones(6, 1);
[I, J, data] = find(K);
I = I - 1;
J = J - 1;
solver(I, J, data, F);
